A recent study shows that 3 out of 4 common cases of blindness in the elderly are triggered by two genes which suffer mutations. Professor Rando Allikmets, from the Columbia University in New York, leader of the research team, stated: "I am not aware of any other complex disorder where nearly 75 per cent of genetic causality has been identified." Macular degeneration causes the progressive loss of sight because of the damage caused to the macula, a sensitive portion in the retina, responsible for fine and detailed vision. The disease destroys central vision, eventually causing blindness. The illness has been known to have a genetic component, this information being confirmed when the study found the two suspicious genes. They play an important part in the body's health: one gene, factor B, activates inflammation, while the other, factor H, causes the disorder, producing a protein which helps shut down the response to a bacterial or a viral infection. The mutated versions can cause extended inflammation, harming the retina. According to the study, "you lose your central vision, so you really can't see in front of you, you can't read properly, you can't drive, you can't watch TV. The worst-case scenario is that you end up legally blind." For now, the study shows that the immune system plays an important part in the development of macular degeneration. Considering the new data, new treatments can lead to improving the disease or stopping it from worsening. The disease affected 50 million people in the world so far.